JPWO2018159857A1 - Welding method and welding equipment - Google Patents

Abstract

The processing target is arranged in a region irradiated with the laser light from the laser device, and the laser light from the laser device is irradiated toward the processing target and moved relatively to the laser light and the processing target. While sweeping the laser light on the processing target, melting and irradiating the irradiated target of the processing target, the laser beam includes a main beam and at least one of the main beam forward in the sweeping direction. The partial beam is composed of a sub beam, and the power density of the main beam is equal to or higher than the power density of the sub beam.

Description

  The present invention relates to a welding method and a welding device.

  Laser welding is known as one of the methods for welding metal materials such as iron and copper. Laser welding is a welding method in which laser light is applied to a welding portion to be processed and the welding portion is melted by the energy of the laser light. A liquid pool of a molten metal material called a molten pool is formed in the welded portion irradiated with the laser light, and then the metal material in the molten pool is solidified to perform welding.

  Further, when irradiating the processing object with the laser light, the profile of the laser light may be shaped according to the purpose. For example, there is known a technique of shaping a profile of laser light when the laser light is used for cutting a processing target (see, for example, Patent Document 1).

  In the past, because the output of the laser light generator was low, laser welding was used for metal materials with low reflectance (high absorption). Also, laser welding is being put to practical use for metal materials having high reflectance such as copper and aluminum (see, for example, Patent Documents 2 to 4).

Japanese Patent Publication No. 2010-508149 JP-A-7-214369 JP 2004-192948 A International Publication No. 2010/131298

  By the way, during welding, it is known that scattered matter called spatter is generated from this molten pool. This spatter is a dispersion of molten metal, and reducing the generation thereof is important for preventing processing defects. The generated spatter adheres to the periphery of the welded portion, but if it is subsequently peeled off and adheres to an electric circuit or the like, it causes an abnormality in the electric circuit. Therefore, it is difficult to weld parts for electric circuits. Further, since the spatter is a molten metal scattered, when spatter is generated, the metal material at the welding point is reduced. That is, when the amount of spatters increases, the metal material at the welded portion becomes insufficient, which may lead to poor strength and the like.

  Further, even if the output of the laser light generator is improved, the reflectance of the metal material does not change, and it is necessary to irradiate the laser light with an intensity sufficient to compensate for the high reflectance. In particular, when the object to be processed begins to melt, it is necessary to irradiate with high-intensity laser light in order to compensate for the high reflectance, but once melting begins, the high reflectance also decreases, and the laser light intensity becomes excessive. turn into. This excess energy of the laser light causes an increase in evaporated metal and unnecessary turbulence in the molten metal, increasing the possibility of welding defects such as spatter and voids.

  The present invention has been made in view of the above, and an object thereof is to provide a welding method and a welding apparatus that suppress the generation of spatter.

  In order to solve the above-mentioned problems and achieve the object, a welding method according to one aspect of the present invention, a processing target is arranged in a region irradiated with laser light from a laser device, While irradiating the laser beam toward the processing target, the laser beam and the processing target are moved relative to each other, and the laser beam is swept on the processing target while melting the irradiated portion of the processing target. And the welding is performed. The laser light is composed of a main beam and a sub-beam having at least a part thereof in front of the sweep direction, and the power density of the main beam is equal to or higher than the power density of the sub-beam.

  In the welding method according to the aspect of the present invention, the power density of the main beam is at least strong enough to generate a keyhole.

  In the welding method according to the aspect of the present invention, the laser beam further includes a sub-beam having a power density lower than that of the main beam, behind the main beam in a sweep direction.

  In the welding method according to the aspect of the present invention, the laser light further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of the main beam in a sweep direction.

  In the welding method according to the aspect of the present invention, the laser beam further includes sub-beams having a power density lower than that of the main beam dispersed around the main beam.

  In the welding method according to the aspect of the present invention, the sub beam has a ring shape surrounding the periphery of the main beam or an arc shape that is a part of the ring shape surrounding the periphery of the main beam.

  In the welding method according to an aspect of the present invention, the main beam and the sub-beam of the laser light have a molten pool formed by the main beam and at least a part of the molten pool formed by the sub-beam overlap. It is configured like.

  In the welding method according to the aspect of the present invention, the wavelength of the laser beam that forms at least the sub beam of the main beam and the sub beam has a reflectance lower than the reflectance in the infrared region of the processing target. Wavelength.

  In the welding method according to the aspect of the present invention, the wavelength of the laser beam forming the main beam is the same as the wavelength of the laser beam forming the sub beam.

  In the welding method according to the aspect of the present invention, the main beam and the sub beam are laser beams emitted from the same oscillator.

  In the welding method according to the aspect of the present invention, the main beam and the sub beam are laser beams emitted from different oscillators.

  In the welding method according to the aspect of the present invention, the main beam and the sub beam are formed by a bee shaper arranged between the oscillator and the processing target.

  In the welding method according to the aspect of the present invention, the beam shaper is a diffractive optical element.

  In the welding method according to an aspect of the present invention, the processing target is at least two members to be welded, and the step of arranging the processing target in a region irradiated with a laser beam includes the at least two members. It is a step of overlapping, contacting, or arranging so as to be adjacent.

  In the welding method according to the aspect of the present invention, the beam diameter of the sub beam is substantially equal to or larger than the beam diameter of the main beam.

  A laser welding device according to an aspect of the present invention receives a laser oscillator and light oscillated from the laser oscillator to generate laser light, and the generated laser light is irradiated toward a processing target. An optical head that melts and welds a portion of the processing target, and the optical head is configured such that the laser light and the processing target are relatively movable, and the laser light is processed by the processing. While sweeping on the target, performing the melting and welding, the laser light is composed of a main beam and a sub-beam at least a part of which is ahead of the sweep direction, and the power density of the main beam is the power of the sub-beam. It is more than density.

  In the laser welding apparatus according to the aspect of the present invention, the power density of the sub beam is at least a strength capable of melting the processing target.

  In the laser welding apparatus according to the aspect of the present invention, the laser beam further includes a sub-beam having a power density lower than that of the main beam, behind the main beam in a sweeping direction.

  In the laser welding apparatus according to the aspect of the present invention, the laser light further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of the main beam in a sweep direction.

  In the laser welding apparatus according to the aspect of the present invention, the laser light further includes sub-beams having a power density lower than that of the main beam dispersed around the main beam.

  In the laser welding apparatus according to the aspect of the present invention, the sub beam has a ring shape surrounding the periphery of the main beam or an arc shape that is a part of the ring shape surrounding the periphery of the main beam.

  In the laser welding apparatus according to an aspect of the present invention, the main beam and the sub-beam of the laser light are a molten pool formed by the main beam, and at least a part of the molten pool formed by the sub-beam. It is configured to overlap.

  In the laser welding apparatus according to an aspect of the present invention, the wavelength of the laser beam that forms at least the sub beam of the main beam and the sub beam has a reflectance lower than the reflectance in the infrared region of the processing target. It is the wavelength that it has.

  In the laser welding apparatus according to the aspect of the present invention, the wavelength of the laser beam that forms the main beam is the same as the wavelength of the laser beam that forms the sub beam.

  In the laser welding apparatus according to the aspect of the present invention, the optical head generates the laser light including the main beam and the sub beam from the light emitted from a single laser oscillator.

  In the laser welding apparatus according to the aspect of the present invention, the optical head includes a beam shaper arranged between the laser oscillator and the processing target, and the diffractive optical element is light oscillated from the single laser oscillator. To form the main beam and the sub beam.

  In the laser welding apparatus according to the aspect of the present invention, the beam shaper is a diffractive optical element.

  In the laser welding apparatus according to an aspect of the present invention, the laser oscillator is composed of two different laser oscillators, and the main beam and the sub-beam are laser beams emitted from the two different oscillators, respectively.

  In the laser welding apparatus according to one aspect of the present invention, the processing target is at least two members to be welded.

  In the laser welding apparatus according to the aspect of the present invention, the beam diameter of the sub beam is substantially equal to or larger than the beam diameter of the main beam.

  In the laser welding apparatus according to the aspect of the present invention, the beam shaper is rotatably provided.

  In the laser welding apparatus according to one aspect of the present invention, the laser oscillator is provided in plurality, and the optical head internally combines lights emitted from the oscillators to generate the laser light.

  The laser welding device according to one aspect of the present invention includes a plurality of the laser oscillators, and further includes a multi-core fiber that multiplexes light emitted from the plurality of laser oscillators inside and guides the combined light to the optical head.

  In the laser welding apparatus according to one aspect of the present invention, the optical head is configured to be capable of sweeping the laser light with respect to the fixed processing target.

  In the laser welding apparatus according to one aspect of the present invention, the irradiation position of the laser light from the optical head is fixed, and the processing target is held movably with respect to the fixed laser light.

  INDUSTRIAL APPLICABILITY The welding method and welding apparatus according to the present invention have the effect of suppressing the generation of spatter.

FIG. 1 is a diagram showing a schematic configuration of a welding device according to the first embodiment. FIG. 2A is a diagram showing a comparison of situations in which laser light melts a processing target. FIG. 2B is a diagram showing a comparison of situations where laser light melts a processing target. FIG. 3A is a diagram showing an example of a cross-sectional shape of laser light. FIG. 3B is a diagram showing an example of a cross-sectional shape of laser light. FIG. 3C is a diagram showing an example of a cross-sectional shape of laser light. FIG. 3D is a diagram showing an example of a cross-sectional shape of laser light. FIG. 3E is a diagram showing an example of a cross-sectional shape of laser light. FIG. 3F is a diagram showing an example of a cross-sectional shape of laser light. FIG. 4 is a diagram showing a schematic configuration of the welding device according to the second embodiment. FIG. 5: is a figure which shows schematic structure of the welding apparatus which concerns on 3rd Embodiment. FIG. 6 is a diagram showing a schematic configuration of a welding device according to the fourth embodiment. FIG. 7: is a figure which shows schematic structure of the welding apparatus which concerns on 5th Embodiment. FIG. 8: is a figure which shows schematic structure of the welding apparatus which concerns on 6th Embodiment. FIG. 9A is a diagram showing a configuration example of an optical fiber. FIG. 9B is a diagram showing a configuration example of an optical fiber. FIG. 10 is a diagram showing a cross-sectional shape of the laser beam used in the experiment. FIG. 11 is a diagram showing an example of a cross-sectional shape of laser light. FIG. 12 is a diagram showing an example of the cross-sectional shape of laser light. FIG. 13 is a graph showing the reflectance of a typical metal material with respect to the wavelength of light. FIG. 14A is a diagram showing a comparison of situations in which laser light melts a processing target. FIG. 14B is a diagram showing a comparison of situations in which laser light melts a processing target. FIG. 15 is a diagram illustrating the concept of the diffractive optical element.

  Hereinafter, a welding method and a welding apparatus according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below. It should be noted that the drawings are schematic, and the dimensional relationship of each element and the ratio of each element may be different from reality. Even between the drawings, there are cases where parts having different dimensional relationships and ratios are included.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of a welding device according to the first embodiment. As shown in FIG. 1, the welding apparatus 100 according to the first embodiment is an example of a configuration of an apparatus that irradiates the processing target W with the laser light L to melt the processing target W. As shown in FIG. 1, the welding apparatus 100 includes an oscillator 110 that oscillates a laser beam, an optical head 120 that irradiates the processing target W with the laser beam, and a light that guides the laser beam oscillated by the oscillator 110 to the optical head 120. And a fiber 130. The workpiece W is at least two members to be welded.

  The oscillator 110 is configured to be able to oscillate a multimode laser beam having an output of, for example, several kW. For example, the oscillator 110 may be configured to include a plurality of semiconductor laser elements therein and to oscillate a multimode laser beam having an output of several kW as a total output of the plurality of semiconductor laser elements. Various lasers such as a fiber laser, a YAG laser, and a disk laser may be used.

  The optical head 120 is an optical device for condensing the laser light L guided from the oscillator 110 to a power density having an intensity capable of melting the object W to be processed and irradiating the object W to be processed. Therefore, the optical head 120 includes a collimator lens 121 and a condenser lens 122 inside. The collimator lens 121 is an optical system for once collimating the laser light guided by the optical fiber 130, and the condensing lens 122 is for converging the collimated laser light on the processing target W. It is an optical system.

  The optical head 120 is provided so that the relative position with respect to the processing target W can be changed in order to move (sweep) the irradiation position of the laser light L on the processing target W. The method of changing the relative position with respect to the processing target W includes moving the optical head 120 itself, moving the processing target W, and the like. That is, the optical head 120 may be configured to be capable of sweeping the laser light L with respect to the fixed processing target W, or the irradiation position of the laser light L from the optical head 120 is fixed and the processing target W is fixed. However, it may be held so as to be movable with respect to the fixed laser light L. In the step of disposing the processing target W in the region irradiated with the laser light L, at least two members to be welded are arranged so as to be overlapped with each other, to be in contact with each other, or to be adjacent to each other.

  The optical head 120 according to the first embodiment includes a diffractive optical element 123 as a beam shaper between the collimator lens 121 and the condenser lens 122. The diffractive optical element here refers to an optical element 1502 in which a plurality of diffraction gratings 1501 having different periods are integrated into one body as in the concept shown in FIG. The laser light that has passed through this is bent in the direction affected by each diffraction grating and overlaps with each other to form laser light in an arbitrary shape. In the present embodiment, in the diffractive optical element 123, the profile of the power density of the laser light L on the processing target W in the moving direction has a lower power density than the main beam in the moving direction ahead of the main beam with high power density. It is for shaping the laser light L so as to have a sub beam. The diffractive optical element 123 may be rotatably provided. Further, it may be configured to be replaceable.

Here, the power density of the main beam or the sub-beam is a power density in a region including a peak and having an intensity equal to or higher than 1 / e ² of the peak intensity. The beam diameter of the main beam or the sub-beam is a diameter of a region including a peak and having an intensity of 1 / e ² or more of the peak intensity. In the case of a non-circular beam, in this specification, the length of a region perpendicular to the moving direction and having an intensity of 1 / e ² or more of the peak intensity is defined as a beam diameter. The beam diameter of the sub beam may be substantially equal to or larger than the beam diameter of the main beam.

  The profile of the power density of the laser light L on the processing target W in the moving direction has a sub-beam whose power density is lower than that of the main beam in the moving direction ahead of the main beam having high power density. On the street. 2A and 2B are diagrams showing a comparison of situations in which laser light melts a processing target.

  As shown in FIG. 2A, in the conventional laser welding, since the laser beam has one beam B, the processing target W moves from the position irradiated with the laser beam in the direction opposite to the moving direction (arrow v). The molten molten pool WP is formed as a molten region. On the other hand, as shown in FIG. 2B, in the welding apparatus and the welding method using the same according to the first embodiment, the profile regarding the moving direction of the power density of the laser light on the processing target W has a main beam B1 and a sub beam B2. And have. The power density of the main beam B1 is, for example, an intensity that can generate at least a keyhole. The keyhole will be described later in detail. Then, a sub beam B2 having a lower power density than the main beam B1 is provided in front of the main beam B1 having a high power density in the moving direction (arrow v). Further, the power density of the sub-beam B2 is a strength capable of melting the processing target W in the presence of the main beam B1 or alone. Therefore, the molten pool WP1 having a region shallower than the depth at which the main beam B1 is melted is formed as a molten region in front of the position where the main beam B1 is irradiated. This will be referred to as a shallow region R for convenience.

  As shown in FIG. 2B, the melting intensity regions of the laser beams of the main beam B1 and the sub-beam B2 may overlap, but they do not necessarily have to overlap, and the molten pools may overlap. Before the molten pool formed by the sub beam B2 is solidified, the molten strength region formed by the main beam B1 may reach the molten pool. As described above, the power densities of the main beam B1 and the sub beam B2 are strengths capable of melting the processing target W, and the melting strength region can melt the processing target W around the main beam B1 or the sub beam B2. It refers to the range of the beam of laser light of power density.

  In the welding apparatus and the welding method using the same according to the first embodiment, since the shallow region R exists ahead of the position where the main beam B1 is irradiated, the molten pool WP1 near the irradiation position of the main beam B1. Stabilizes. As described above, since the molten metal is scattered in the spatter, the stabilization of the molten pool WP1 in the vicinity of the irradiation position of the main beam B1 leads to the suppression of spatter generation. In fact, the experiment to be described later confirmed the effect of suppressing the generation of spatter.

  In the welding method according to the first embodiment, the processing target W is arranged in a region irradiated with the laser light L from the oscillator 110, which is a laser device, and the laser light L from the oscillator 110 is irradiated toward the processing target W. While the laser light L and the processing target W are moved relative to each other, and the laser light L is swept on the processing target W, the irradiated processing target W is melted and welded. At this time, the laser beam L is composed of the main beam B1 and the sub-beam B2 having at least a part thereof in the front in the sweep direction, and the power density of the main beam B1 is equal to or higher than the power density of the sub-beam B2. The workpiece W is at least two members to be welded. The step of arranging the processing target W in the region irradiated with the laser light L is a step of arranging at least two members so as to overlap, contact, or be adjacent to each other.

  The power density of the sub-beam B2 is such that the shallow region R is deeper than the diameter of allowable porosity (void, pit with holes from the inside to the surface, welding defects such as blow holes). The density is preferable. As a result, the impurities adhering to the surface of the processing target W, which is one of the causes of porosity, flow in the shallow region R and into the molten pool WP1 formed by the main beam B1, so that porosity is less likely to occur. The allowable diameter of porosity is determined according to the intended use of the processing target W, for example. Generally, 200 μm or less is allowed, 100 μm or less is preferable, 50 μm or less is more preferable, 30 μm or less is more preferable, 20 μm or less is even more preferable, 10 μm or less is even more preferable, and the absence thereof is most preferable.

  Next, with reference to FIGS. 3A to 3F, the profile of the power density of the laser light in the moving direction on the processing target is such that a sub beam having a power density lower than that of the main beam is ahead of the main beam having high power density in the moving direction. An example of a cross-sectional shape of laser light for having a beam will be described. The example of the cross-sectional shape of the laser light shown in FIGS. 3A to 3F is not an indispensable configuration, but diffractive optics is used so that the cross-sectional shape of the laser light illustrated in FIGS. By designing the element 123, a laser light profile suitable for implementing the present invention is realized. The cross-sectional shapes of the laser light illustrated in FIGS. 3A to 3F all have the moving direction above the paper surface (arrow v in the drawing).

  FIG. 3A is an example in which one sub-beam B2 having a peak P2 and having a power density lower than that of the main beam B1 is provided ahead of the main beam B1 having the peak P1 and having a high power density in the moving direction. As shown in FIG. 3A, the region of power density around the sub-beam B2 that can melt the object to be processed is more orthogonal to the moving direction than the region around the main beam B1 that can melt the object to be processed. It is preferably wide. Therefore, as shown in FIG. 3A, the sub-beam B2 may be expanded into a continuous area without forming a point shape.

  FIG. 3B shows that not only the sub-beam B2 having a lower power density than the main beam B1 is provided in front of the main beam B1 having a high power density in the moving direction, but also the sub-beam B2 having a power density lower than that of the main beam B1 in the moving direction is provided. Is an example having the sub-beam B2 having a low power density. Welding may be performed not only in the forward direction but also in the backward direction. Therefore, as in the example shown in FIG. 3B, if the sub-beam B2 having a lower power density than the main beam B1 is provided behind the main beam B1 in the moving direction, the present invention can be performed without changing the direction of the optical head. The effect can be obtained.

  FIG. 3C shows that not only the auxiliary beam B2 having a power density lower than that of the main beam B1 is provided ahead of the main beam B1 having a high power density in the moving direction, but also the main beam B1 is provided in the lateral direction of the movement of the main beam B1. This is an example in which the sub beam B2 having a lower power density is used. Welding is not always performed along a straight line. Therefore, as in the example shown in FIG. 3C, if the sub-beam B2 having a power density lower than that of the main beam B1 is provided laterally in the moving direction of the main beam B1, the present invention can be performed even at the corner welding. The effect of can be obtained.

  FIG. 3D shows that not only the auxiliary beam B2 having a lower power density than the main beam B1 is provided ahead of the main beam B1 having a high power density in the moving direction, but also in the backward and lateral directions of the main beam B1 in the moving direction. This is an example in which the sub beam B2 having a power density lower than that of the main beam B1 is provided. That is, the example shown in FIG. 3D has both advantages of the examples shown in FIGS. 3B and 3C.

  FIG. 3E is an example in which sub-beams B2 having a power density lower than that of the main beam B1 are dispersed around the main beam B1. In the example shown in FIGS. 3A to 3D, the sub-beam B2 is linearly configured, but the sub-beams B2 do not necessarily need to be continuous if the sub-beams B2 are arranged at a certain distance. This is because if the sub-beams B2 are arranged at a certain distance close to each other, the shallow regions R are connected, and an effective effect can be obtained. FIG. 3F is an example in which a sub-beam B2 having a power density lower than that of the main beam B1 is provided in a ring shape around the main beam B1. Contrary to FIG. 3E, it is also possible to provide the sub-beam B2 in such a form that it makes one round continuously.

  The distance d (for example, shown in FIG. 3A) between the main beam B1 and the sub beam B2 is the shortest distance between the outer edge of the beam diameter of the main beam B1 and the outer edge of the beam diameter of the sub beam B2. The distance d may be such that the molten region formed by the main beam B1 can reach the molten pool formed by the sub beam B2 before it solidifies, but is preferably less than twice the beam diameter of the sub beam B2. Less than 1 time is more preferable, and less than 0.5 time is further preferable.

  Further, the power densities of the main beam B1 and the sub beam B2 may be the same.

(Second embodiment)
FIG. 4 is a diagram showing a schematic configuration of the welding device according to the second embodiment. As shown in FIG. 4, the welding apparatus 200 according to the second embodiment is an example of the configuration of an apparatus that irradiates the processing target W with the laser light L to melt the processing target W. The welding apparatus 200 according to the second embodiment realizes a welding method according to the same operation principle as that of the welding apparatus according to the first embodiment. Therefore, only the device configuration of the welding device 200 will be described below.

  As shown in FIG. 4, the welding device 200 includes an oscillator 210 that oscillates a laser beam, an optical head 220 that irradiates the processing target W with the laser beam, and a light that guides the laser beam oscillated by the oscillator 210 to the optical head 220. And a fiber 230.

  The oscillator 210 is configured to be capable of oscillating multimode laser light having an output of, for example, several kW. For example, the oscillator 210 may be configured to include a plurality of semiconductor laser elements therein and to oscillate multimode laser light having an output of several kW as a total output of the plurality of semiconductor laser elements. Various lasers such as a fiber laser, a YAG laser, and a disk laser may be used.

  The optical head 220 is an optical device for converging the laser light L guided from the oscillator 210 to a power density having an intensity capable of melting the processing target W and irradiating the processing target W with the power. Therefore, the optical head 220 includes a collimator lens 221 and a condenser lens 222 inside. The collimating lens 221 is an optical system for once collimating the laser light guided by the optical fiber 230, and the condensing lens 222 is for converging the collimated laser light on the processing target W. It is an optical system.

  The optical head 220 has a galvano scanner between the condenser lens 222 and the processing target W. The galvano scanner is a device that can move the irradiation position of the laser light L without moving the optical head 220 by controlling the angles of the two mirrors 224a and 224b. In the example shown in FIG. 4, a mirror 226 is provided to guide the laser light L emitted from the condenser lens 222 to the galvano scanner. The angles of the mirrors 224a and 224b of the galvano scanner are changed by motors 225a and 225b, respectively.

  The optical head 220 according to the second embodiment includes a diffractive optical element 223 between the collimator lens 221 and the condenser lens 222. The diffractive optical element 223 has a profile in which the power density of the laser light L on the processing target W in the moving direction has a sub-beam having a lower power density than the main beam in the moving direction ahead of the main beam having a high power density. In addition, it is for molding the laser light L, and its action is the same as that of the first embodiment. That is, the diffractive optical element 223 is designed to realize a laser light profile suitable for implementing the present invention, such as the cross-sectional shape of the laser light illustrated in FIGS.

(Third Embodiment)
FIG. 5: is a figure which shows schematic structure of the welding apparatus which concerns on 3rd Embodiment. As shown in FIG. 5, the welding apparatus 300 according to the third embodiment is an example of the configuration of an apparatus that irradiates the processing target W with the laser light L to melt the processing target W. The welding apparatus 300 according to the third embodiment realizes the welding method by the same operation principle as the welding apparatus according to the first embodiment, and the configuration (oscillator 310 and optical fiber 330) other than the optical head 320 is This is similar to the second embodiment. Therefore, only the device configuration of the optical head 320 will be described below.

  The optical head 320 is an optical device for condensing the laser light L guided from the oscillator 310 to a power density having an intensity capable of melting the processing target W and irradiating the processing target W with the power. Therefore, the optical head 320 includes a collimator lens 321 and a condenser lens 322 inside. The collimator lens 321 is an optical system for once collimating the laser light guided by the optical fiber 330, and the condenser lens 322 is for converging the collimated laser light on the processing target W. It is an optical system.

  The optical head 320 has a galvano scanner between the collimator lens 321 and the condenser lens 322. The angles of the mirrors 324a and 324b of the galvano scanner are changed by motors 325a and 325b, respectively. The optical head 320 is provided with a galvano scanner at a position different from that of the second embodiment. Similarly, by controlling the angles of the two mirrors 324a and 324b, the laser light can be moved without moving the optical head 320. The irradiation position of L can be moved.

  The optical head 320 according to the third embodiment includes a diffractive optical element 323 between the collimator lens 321 and the condenser lens 322. The diffractive optical element 323 has a profile in the moving direction of the power density of the laser light L on the processing target W such that it has a sub-beam whose power density is lower than that of the main beam ahead of the main beam having high power density in the moving direction. In addition, it is for molding the laser light L, and its action is the same as that of the first embodiment. That is, the diffractive optical element 323 is designed to realize a laser light profile suitable for implementing the present invention, such as the cross-sectional shape of the laser light illustrated in FIG.

(Fourth Embodiment)
FIG. 6 is a diagram showing a schematic configuration of a welding device according to the fourth embodiment. As shown in FIG. 6, the welding apparatus 400 according to the fourth embodiment is an example of the configuration of an apparatus that irradiates the processing target W with the laser beams L1 and L2 to melt the processing target W. The welding device 400 according to the fourth embodiment realizes a welding method according to the same operation principle as that of the welding device according to the first embodiment. Therefore, only the device configuration of the welding device 400 will be described below.

  As shown in FIG. 6, the welding apparatus 400 includes a plurality of oscillators 411 and 412 that oscillate laser light, an optical head 420 that irradiates the processing target W with the laser light, and laser light oscillated by the oscillators 411 and 412. The optical fibers 431 and 432 are guided to the optical head 420.

  The oscillators 411 and 412 are configured to be able to oscillate, for example, multimode laser light having an output of several kW. For example, each of the oscillators 411 and 412 is provided with a plurality of semiconductor laser elements inside, and is configured to be capable of oscillating a multi-mode laser beam having an output of several kW as a total output of the plurality of semiconductor laser elements. Alternatively, various lasers such as a fiber laser, a YAG laser, and a disk laser may be used.

  The optical head 420 is an optical device for converging the respective laser beams L1 and L2 guided from the oscillators 411 and 412 to a power density having an intensity capable of melting the processing target W and irradiating the processing target W with the power density. is there. Therefore, the optical head 420 includes a collimator lens 421a and a condenser lens 422a for the laser light L1, and a collimator lens 421b and a condenser lens 422b for the laser light L2. The collimator lenses 421a and 421b are optical systems for temporarily collimating the laser light guided by the optical fibers 431 and 432, respectively. The condenser lenses 422a and 422b process the collimated laser light. It is an optical system for focusing light on the target W.

  Also in the optical head 420 according to the fourth embodiment, the profile of the power density of the laser beams L1 and L2 on the processing target W in the moving direction is forward of the main beam having a high power density in the moving direction and is higher than that of the main beam. Are configured to have a low side beam. That is, of the laser beams L1 and L2 that the optical head 420 irradiates the processing target W, the laser beam L1 may be used for forming the main beam and the laser beam L2 may be used for forming the sub beam. Although the example shown in the figure uses only the laser beams L1 and L2, it is suitable for implementing the present invention, such as the cross-sectional shape of the laser beam illustrated in FIG. 3, by appropriately increasing the number. Can be configured to achieve different laser light profiles.

(Fifth Embodiment)
FIG. 7: is a figure which shows schematic structure of the welding apparatus which concerns on 5th Embodiment. As shown in FIG. 7, the welding apparatus 500 according to the fifth embodiment is an example of the configuration of an apparatus that irradiates the processing target W with the laser beams L1 and L2 to melt the processing target W. The welding apparatus 500 according to the fifth embodiment realizes a welding method by the same operation principle as the welding apparatus according to the first embodiment. Therefore, only the device configuration of the welding device 500 will be described below.

  As shown in FIG. 7, the welding apparatus 500 includes an oscillator 510 that oscillates a laser beam, an optical head 520 that irradiates the processing target W with the laser beam, and a light that guides the laser beam oscillated by the oscillator 510 to the optical head 520. Fibers 531, 533 and 534 are provided.

  In the fifth embodiment, the oscillator 510 is, for example, a fiber laser, a YAG laser, a disk laser, or the like, and is used to oscillate both the laser beams L1 and L2 with which the processing target W is irradiated. Therefore, a branching unit 532 is provided between the optical fibers 531, 533 and 534 for guiding the laser light oscillated by the oscillator 510 to the optical head 520, and the optical head is branched after the laser light oscillated by the oscillator 510. It is configured to lead to 520.

  The optical head 520 is an optical device for converging the laser beams L1 and L2 branched by the branching unit 532 to a power density having an intensity capable of melting the processing target W and irradiating the processing target W with the power density. Therefore, the optical head 520 includes a collimator lens 521a and a condenser lens 522a for the laser light L1, and a collimator lens 521b and a condenser lens 522b for the laser light L2. The collimating lenses 521a and 521b are optical systems for temporarily collimating the laser light guided by the optical fibers 533 and 534, respectively, and the condenser lenses 522a and 522b process the collimated laser light. It is an optical system for focusing light on the target W.

  Also in the optical head 520 according to the fifth embodiment, the profile of the power density of the laser beams L1 and L2 on the processing target W in the moving direction has a power density higher than that of the main beam in the moving direction ahead of the main beam with high power density. Are configured to have a low side beam. That is, of the laser beams L1 and L2 that the optical head 520 irradiates the processing target W, the laser beam L1 may be used for forming the main beam and the laser beam L2 may be used for forming the sub beam. Although the example shown in the figure uses only the laser beams L1 and L2, it is suitable for implementing the present invention, such as the cross-sectional shape of the laser beam illustrated in FIG. 3, by appropriately increasing the number. Can be configured to achieve different laser light profiles.

(Sixth Embodiment)
FIG. 8: is a figure which shows schematic structure of the welding apparatus which concerns on 6th Embodiment. As shown in FIG. 8, the welding apparatus 600 according to the sixth embodiment is an example of the configuration of an apparatus that irradiates the processing target W with the laser light L to melt the processing target W. The welding apparatus 600 according to the sixth embodiment realizes a welding method according to the same operation principle as the welding apparatus according to the first embodiment. Therefore, only the device configuration of the welding device 600 will be described below.

  As shown in FIG. 8, the welding device 600 includes a plurality of oscillators 611 and 612 that oscillate a laser beam such as a fiber laser, a YAG laser, and a disk laser, and an optical head 620 that irradiates the processing target W with the laser beam. , Optical fibers 631, 632, 635 for guiding the laser light oscillated by the oscillators 611, 612 to the optical head 620.

  In the sixth embodiment, the laser lights oscillated by the oscillators 611 and 612 are combined before being guided to the optical head 620. Therefore, a coupling unit 634 is provided between the optical fibers 631, 632 and 635 that guide the laser light oscillated by the oscillators 611 and 612 to the optical head 620, and the laser light oscillated by the oscillators 611 and 612 is It will be guided in parallel in the fiber 635.

  Here, a configuration example of the optical fiber 631 (and 632) and the optical fiber 635 will be described with reference to FIGS. 9A and 9B. As shown in FIG. 9A, the optical fiber 631 (and 632) is a normal optical fiber. That is, the optical fiber 631 (and 632) is an optical fiber in which the cladding Cl having a refractive index lower than that of the core Co is formed around one core Co. On the other hand, as shown in FIG. 9B, the optical fiber 635 is a so-called multi-core optical fiber. That is, the optical fiber 635 has two cores Co1 and Co2, and the cladding Cl having a lower refractive index than the cores Co1 and Co2 is formed around the two cores Co1 and Co2. Then, in the coupling section 634, the core Co of the optical fiber 631 and the core Co1 of the optical fiber 635 are coupled, and the core Co of the optical fiber 632 and the core Co2 of the optical fiber 635 are coupled.

  Returning to the reference of FIG. The optical head 620 is an optical device for condensing the laser light L coupled by the coupling unit 634 to a power density having an intensity capable of melting the processing target W and irradiating the processing target W with the power. Therefore, the optical head 620 includes a collimator lens 621 and a condenser lens 622 inside.

  In the present embodiment, the optical head 620 does not include a diffractive optical element and does not have an independent optical system for a plurality of laser beams, but the laser beams oscillated by the oscillators 611 and 612 are optical. Since the laser beam L is coupled before being guided to the head 620, the profile of the power density of the laser light L on the processing target W in the moving direction has a power density higher than that of the main beam in the moving direction ahead of the main peak with high power density. Are configured to have a low side beam.

  In addition, with respect to all the embodiments of the present specification, the welding form of the main beam may be keyhole type welding or heat conduction type welding. The keyhole welding here is a welding method using a high power density and utilizing a recess or a hole (keyhole) generated by the pressure of the metal vapor generated when the processing target W is melted. On the other hand, the heat conduction type welding is a welding method in which the workpiece W is melted by utilizing the heat generated by the absorption of the laser light on the surface of the base material.

(Verification experiment 1)
Here, the result of the verification experiment 1 of the effect of the present invention will be described. The apparatus configuration used in this verification experiment 1 is the configuration of the welding apparatus 100 according to the first embodiment, and the configuration excluding the diffractive optical element 123 from the welding apparatus 100 was used as the apparatus configuration of the conventional example. As common experimental conditions, the output of the oscillator 110 is 3 kW, the relative moving speed between the optical head 120 and the processing target W is 5 m / min, and nitrogen gas is used as a shield gas.

  The diffractive optical element 123 is formed by a main beam B1 having a peak P1 and a sub-beam B2 having a peak P2 as shown in FIG. 10, and the sub-beam B2 has a ring shape surrounding the main beam B1. It is designed so that the cross-sectional shape of the arc-shaped laser light, which is the portion, is irradiated onto the processing target W. The generation of spatter was observed in the two moving directions of the laser beam molded by the diffractive optical element 123, that is, the direction of arrow A in the figure and the direction of arrow B in the figure. In the apparatus configuration of the conventional example, the processing target W is irradiated with the laser light in which the arc portion is deleted from the cross-sectional shape of the laser light shown in FIG.

  That is, in the verification experiment 1, when moving in the direction of the arrow A in the figure, the sub-beam B2 having a lower power density than the main beam B1 is located in front of the main beam B1 having a high power density in the moving direction. Correspondingly, the case of moving in the direction of arrow B in the figure corresponds to the situation in which the sub-beam B2 having a lower power density than the main beam B1 is provided behind the main beam B1 having a high power density in the moving direction. The above configuration corresponds to the situation where only the main beam B1 is irradiated.

  In a situation where only the main beam B1 is irradiated, and a situation where a sub-beam B2 having a power density lower than that of the main beam B1 is provided behind the main beam B1 having a high power density in the moving direction, a large amount of spatter occurs. On the other hand, in the situation where the sub-beam B2 having a lower power density than the main beam B1 is provided ahead of the main beam B1 having a high power density in the moving direction, the occurrence of spatter is significantly reduced to about 20% or less. become.

  Also from this verification experiment 1, the profile in the moving direction of the power density of the laser light L on the processing target W has a sub-peak having a lower power density than the main peak in the moving direction ahead of the main peak with high power density. It has been shown that the welding device and the welding method using the same have the effect of suppressing the generation of spatter.

Further, it was confirmed that the effect was obtained as shown in Table 1 even under the condition that nitrogen gas was not used. Table 1 shows four experiments. The material to be processed is SUS304 and has a thickness of 10 mm. DOE is a diffractive optical element. The focus position is the focus position of the main beam and the sub beam, and the surface is just focused. The set output is the power of the laser light output from the oscillator. Velocity is the sweep velocity. As an appearance, the experiment No. 3 and 4 were favorable results.

  11 and 12 are diagrams showing an example of the cross-sectional shape of the laser beam. The V-shaped sub-beam B2 having a power density lower than that of the main beam B1 is located ahead of the main beam B1 having a high power density in the moving direction. Is an example having. FIG. 11 shows an example in which the main beam B1 and the sub beam B2 overlap, and FIG. 12 shows an example in which the main beam B1 and the sub beam B2 do not overlap.

(Reflectance of metal material)
Here, the reflectance of the metal material will be described. The graph shown in FIG. 13 shows the reflectance of a typical metal material with respect to the wavelength of light. In the graph shown in FIG. 13, the horizontal axis represents wavelength and the vertical axis represents reflectance. Examples of metal materials include aluminum, copper, gold, nickel, platinum, silver, stainless steel, titanium, and tin. It has been described. The graph shown in FIG. 13 is a graph of the data described in NASA TECHNICAL NOTE (D-5353).

  As can be seen from the graph shown in FIG. 13, copper and aluminum have a higher reflectance than stainless steel and the like. In particular, the difference is remarkable in the wavelength region of infrared laser light generally used in laser welding. For example, in the vicinity of 1070 nm, the reflectance of copper and aluminum is about 95%, so that only about 5% of the energy of the irradiated laser light is absorbed by the object to be processed. This means that the efficiency of irradiation energy is about 1/6 of that of stainless steel.

  On the other hand, even if the reflectance of copper or aluminum is high, it does not mean that the reflectance of light of all wavelengths is high. In particular, the change in reflectance of copper is remarkable. As described above, the reflectance of copper in the vicinity of 1070 nm was about 95%, but at the yellow wavelength (for example, 600 nm), the reflectance of copper becomes about 75%, and from there, it sharply decreases, At the wavelength of light (for example, 300 nm), the reflectance of copper is about 20%. Therefore, the energy efficiency of laser welding using blue or green laser light is higher than that of general infrared laser light. Specifically, it is preferable to use laser light having a wavelength between 300 nm and 600 nm.

  Note that the above wavelength range is an example, and if laser welding is performed using a laser beam having a wavelength lower than the reflectance of the target material in the infrared region, energy efficiency is improved in terms of reflectance. High welding can be performed. The infrared region in this case is preferably 1070 nm, which is the wavelength of infrared laser light used for general laser welding.

  The welding method and welding apparatus according to the embodiments of the present invention described below utilize the above characteristics.

(Seventh embodiment)
The welding device according to the seventh embodiment can be realized by the welding device 100 according to the first embodiment shown in FIG.

  The laser oscillator 110 is configured to be capable of oscillating multimode laser light having an output of, for example, several kW. For example, the laser oscillator 110 may be configured to include a plurality of semiconductor laser elements therein and oscillate a multimode laser beam having an output of several kW as a total output of the plurality of semiconductor laser elements. .. In the seventh embodiment, the laser oscillator 110 is preferably configured to oscillate laser light having a wavelength of 300 nm to 600 nm from the above viewpoint. Furthermore, it is more preferable to select the laser oscillator 110 that oscillates at a wavelength at which the reflectance of the processing target W becomes low according to the processing target W.

  The optical head 120 according to the seventh embodiment includes a diffractive optical element 123 as a beam shaper between the collimator lens 121 and the condenser lens 122. The diffractive optical element 123 is for shaping the laser beam L so that the profile of the power density of the laser beam L on the processing target W in the sweep direction has a sub-beam located in front of the main beam in the sweep direction. Is. Therefore, the welding device 100 according to the seventh embodiment has a configuration in which the laser light emitted from the same laser oscillator 110 is separated by the diffractive optical element 123, and as a result, both the main beam and the sub-beam are separated. The wavelengths of the laser beams to be formed are the same. The diffractive optical element 123 may be rotatably provided. Further, it may be configured to be replaceable.

  The effect that the profile of the power density of the laser beam L on the processing target W in the sweep direction has the main beam and the sub-beam located in front of the main beam in the sweep direction is as follows. 14A and 14B are diagrams showing a comparison of situations in which a laser beam melts a processing target.

  As shown in FIG. 14A, in the conventional laser welding, since the laser light has one beam B, the unmelted metal W1 in the sweep direction (arrow v) forward from the position where the laser light is irradiated is the laser beam. A molten pool WP in which the processing target W is melted is formed in a direction opposite to the sweeping direction (arrow v) from the position irradiated with the laser light and melted by the energy of light. After that, the molten pool WP is re-solidified to become the re-solidified metal W2, and the processing target W is welded.

  On the other hand, as shown in FIG. 14B, in the welding apparatus and the welding method using the same according to the eleventh embodiment, the profile of the power density of the laser light on the processing target W in the sweeping direction has main beam B1 and sub beam B2. And have. Then, a sub-beam B2 having a lower power density than the main beam B1 is provided in front of the main beam B1 having a high power density in the sweep direction (arrow v). Further, the power density of the sub-beam B2 is a strength capable of melting the processing target W in the presence of the main beam B1 or alone. Therefore, a molten pool shallower than the depth at which the main beam B1 is melted is formed in front of the position where the main beam B1 is irradiated. This will be referred to as a front molten pool WPf for convenience.

  As shown in FIG. 14B, the melting intensity regions of the laser beams of the main beam B1 and the sub beam B2 do not necessarily have to overlap with each other, and the molten pools may overlap with each other. That is, it is sufficient if the melt strength region formed by the main beam B1 can reach the front molten pool WPf before the molten pool formed by the sub beam B2 is solidified. As described above, the power densities of the main beam B1 and the sub beam B2 are strengths capable of melting the processing target W, and the melting strength region can melt the processing target W around the main beam B1 or the sub beam B2. It refers to the range of the beam of laser light of power density.

  In the welding apparatus and the welding method using the same according to the eleventh embodiment, since the front molten pool WPf exists ahead of the position where the main beam B1 is irradiated, the molten pool near the irradiation position of the main beam B1. The WP state stabilizes. As described above, since the spatter is the molten metal scattered, the stabilization of the state of the molten pool WP near the irradiation position of the main beam B1 leads to the suppression of spatter generation.

  Moreover, in the welding apparatus and the welding method using the same according to the seventh embodiment, at least the sub-beam B2 (both in this example) of the main beam B1 and the sub-beam B2 has a wavelength of the laser beam that is to be processed. Since the wavelength has a reflectance lower than the reflectance in the infrared region, the front molten pool WPf can be efficiently formed even with a metal material having a high reflectance in the infrared wavelength such as copper or aluminum. ..

In the welding device and the welding method using the same according to the seventh embodiment, it is preferable that the power density in the sub beam B2 be lower than the power density in the main beam B1. More specifically, the power density in the sub beam B2 is preferably 1 × 10 ⁷ W / cm ² or less. The purpose of the sub-beam B2 is to form the front molten pool WPf in front of the position where the main beam B1 is irradiated. The state of is to be stabilized. The depth of the front molten pool WPf is sufficient to be stable enough to stabilize the molten pool WP, and as described above, the laser beam forming the sub beam B2 is more than the reflectance in the infrared region of the processing target. Also, since the reflectance with respect to the processing target is reduced by setting the wavelength having a low reflectance, it is not required that the power density is excessively high. If the power density of the sub-beam is too high, the sub-beam itself contributes to the generation of spatter. On the other hand, the purpose of the main beam is to sufficiently melt the workpiece W and reliably weld the workpiece. Considering these, it is preferable that the power density in the sub-beam B2 is lower than the power density in the main beam B1.

  3A to 3F, 11 and 12 are examples of the cross-sectional shape of the laser light because the profile of the power density of the laser light on the processing target in the sweeping direction has the sub-beam located in front of the main beam in the sweeping direction. As shown in.

  Since the laser beam arranged in the sub-beam B2 has a lower power density than the main beam B1 for welding, the original welding work is hindered even if the sub-beam B2 is arranged in a direction other than the intended front direction. There is no such thing. For example, the intensity of the laser beam forming the main beam B1 is set to 1 kW, and the intensity of the laser beam forming the sub beam B2 is set to 300 W.

  As is clear from the example described above, the sub-beam P2 does not necessarily have to have a profile with a single peak value. Even if the profile has a peak value in a certain area (including a linear shape) or a profile in which the points having a peak value are arranged at a certain close distance, it has a substantial effect on the formed molten pool. Because it does not give. Therefore, these will be referred to as sub-beams P2 without distinction.

(Eighth Embodiment)
The welding device according to the eighth embodiment can be realized by the welding device 200 according to the second embodiment shown in FIG.

  The laser oscillator 210 is configured to be capable of oscillating multimode laser light having an output of, for example, several kW. For example, the laser oscillator 210 is provided with a plurality of semiconductor laser elements inside, and is configured to be capable of oscillating multi-mode laser light with an output of several kW as the total output of the plurality of semiconductor laser elements. The laser oscillator 210 is preferably configured to oscillate laser light having a wavelength between 300 nm and 600 nm, as in the eighth embodiment. Furthermore, it is more preferable to select the laser oscillator 210 that oscillates at a wavelength at which the reflectance of the object W to be processed is reduced according to the object W to be processed.

  In the welding device and the welding method using the same according to the eighth embodiment, at least the sub-beam (both in this example) of the main beam and the sub-beam has a wavelength of laser light that reflects in the infrared region of the processing target. Since the wavelength has a reflectance lower than the reflectance, the front molten pool can be efficiently formed even with a metal material having a high reflectance at an infrared wavelength such as copper or aluminum.

(9th Embodiment)
The welding device according to the ninth embodiment can be realized by the welding device 300 according to the third embodiment shown in FIG.

  The optical head 320 includes a diffractive optical element 323 as a beam shaper between the collimator lens 321 and the condenser lens 322. The diffractive optical element 323 is for shaping the laser light L so that the profile of the power density of the laser light L on the processing target W in the sweeping direction has a sub-beam located ahead of the main beam in the sweeping direction. Is. That is, the diffractive optical element 323 is designed to realize a laser light profile suitable for implementing the present invention, such as the cross-sectional shape of the laser light illustrated in FIGS. 3A to 3F, 11, and 12.

  In the welding apparatus and the welding method using the same according to the ninth embodiment, the wavelength of the laser beam forming at least the sub-beam (both in this example) of the main beam and the sub-beam is the reflection in the infrared region of the processing target. Since the wavelength has a reflectance lower than the reflectance, the front molten pool can be efficiently formed even with a metal material having a high reflectance at an infrared wavelength such as copper or aluminum.

(10th Embodiment)
The welding device according to the tenth embodiment can be realized by the welding device 400 according to the fourth embodiment shown in FIG.

  In the tenth embodiment, the laser oscillator 411 and the laser oscillator 412 are different laser oscillators and may oscillate laser lights of the same wavelength, but may be configured to oscillate different laser lights. In that case, the laser oscillator 412 is configured such that the wavelength of the laser beam L2 that forms the sub-beam of the main beam and the sub-beam is between 300 nm and 600 nm.

  The optical head 420 is configured so that the profile of the power densities of the laser beams L1 and L2 on the processing target W in the sweep direction has a sub-beam located ahead of the main beam in the sweep direction. That is, of the laser beams L1 and L2 that the optical head 420 irradiates the processing target W, the laser beam L1 may be used for forming the main beam and the laser beam L2 may be used for forming the sub beam. Although the example shown in the drawing uses only the laser beams L1 and L2, by appropriately increasing the number thereof, such as the cross-sectional shape of the laser beam illustrated in FIGS. 3A to 3F, 11, and 12, It may be configured to realize a laser light profile suitable for implementing the present invention.

  In the welding apparatus and the welding method using the same according to the tenth embodiment, the wavelength of the laser beam that forms at least the sub beam of the main beam and the sub beam has a reflectance lower than the reflectance in the infrared region of the processing target. Therefore, even if it is a metal material having a high reflectance at an infrared wavelength such as copper or aluminum, the front molten pool can be efficiently formed. On the other hand, since the wavelength of the laser beam L1 that forms the main beam does not necessarily have to be a wavelength having a reflectance lower than the reflectance in the infrared region of the processing target, the laser oscillator 411 is similar to the conventional product in that A high power laser oscillator with an infrared wavelength can be used. That is, in the present embodiment, the wavelength of the laser beam that forms the sub-beam has a reflectance that is lower than the reflectance of the processing target at the wavelength of the laser beam that forms the main beam. Even if a metal material having a high reflectance at an infrared wavelength is used, the reflectance becomes low in a molten state. Therefore, the laser oscillator 411 is, for example, a high-power laser oscillator at an infrared wavelength such as a fiber laser, a YAG laser, or a disk laser. Even if used, the object to be processed can be sufficiently melted.

(Eleventh Embodiment)
The welding device according to the eleventh embodiment can be realized by the welding device 500 according to the fifth embodiment shown in FIG. 7.

  The optical head 520 is configured so that the profile of the power densities of the laser beams L1 and L2 on the processing target W in the sweep direction has a sub-beam located in front of the main beam in the sweep direction. That is, of the laser beams L1 and L2 that the optical head 520 irradiates the processing target W, the laser beam L1 may be used for forming the main beam and the laser beam L2 may be used for forming the sub beam. Although the example shown in the drawing uses only the laser beams L1 and L2, by appropriately increasing the number thereof, such as the cross-sectional shape of the laser beam illustrated in FIGS. 3A to 3F, 11, and 12, It may be configured to realize a laser light profile suitable for implementing the present invention.

  In the welding apparatus and the welding method using the same according to the eleventh embodiment, the wavelength of the laser beam that forms at least the sub beam (both in this example) of the main beam and the sub beam is the reflection in the infrared region of the processing target. Since the wavelength has a reflectance lower than the reflectance, the front molten pool can be efficiently formed even with a metal material having a high reflectance at an infrared wavelength such as copper or aluminum.

(Twelfth Embodiment)
The welding device according to the twelfth embodiment can be realized by the welding device 600 according to the sixth embodiment shown in FIG.

  In the twelfth embodiment, the laser oscillator 611 and the laser oscillator 612 are different laser oscillators and may oscillate laser lights of the same wavelength, but may be configured to oscillate different laser lights. In that case, the laser oscillator 612 is configured such that the wavelength of the laser light forming the sub beam of the main beam and the sub beam is between 300 nm and 600 nm.

  In the twelfth embodiment, the laser beams oscillated by the laser oscillators 611 and 612 are combined before being guided to the optical head 620. Therefore, a coupling portion 634 is provided between the optical fibers 631, 632 and 635 that guide the laser light oscillated by the laser oscillators 611 and 612 to the optical head 620, and the laser light oscillated by the laser oscillators 611 and 612 is , Are guided in parallel in the optical fiber 635.

  The optical head 620 is an optical device for condensing the laser light L coupled by the coupling unit 634 to a power density having an intensity capable of melting the processing target W and irradiating the processing target W with the power. Therefore, the optical head 620 includes a collimator lens 621 and a condenser lens 622 inside.

  In the present embodiment, the optical head 620 does not include a beam shaper and does not have an independent optical system for a plurality of laser lights, but the laser light oscillated by the laser oscillators 611 and 612 is the optical head. Since they are coupled before being guided to 620, the profile of the power density of the laser light L on the processing target W in the sweep direction is configured to have a sub-beam located ahead of the main beam in the sweep direction. ..

  In the welding apparatus and the welding method using the same according to the twelfth embodiment, the wavelength of the laser beam that forms at least the sub-beam of the main beam and the sub-beam has a reflectance lower than the reflectance in the infrared region of the processing target. Therefore, even if it is a metal material having a high reflectance at an infrared wavelength such as copper or aluminum, the front molten pool can be efficiently formed. On the other hand, since the wavelength of the laser beam L1 that forms the main beam does not necessarily have to be a wavelength having a reflectance lower than the reflectance in the infrared region of the processing target, the laser oscillator 611 is similar to the conventional product in that A high power laser oscillator with an infrared wavelength can be used. That is, in the present embodiment, the wavelength of the laser beam that forms the sub-beam has a reflectance that is lower than the reflectance of the processing target at the wavelength of the laser beam that forms the main beam. Even if a metal material having a high reflectance at an infrared wavelength is used, the reflectance becomes low in a molten state. Therefore, the laser oscillator 611 is, for example, a high-power laser oscillator at an infrared wavelength such as a fiber laser, a YAG laser, or a disk laser. Even if used, the object to be processed can be sufficiently melted.

  For all the above-mentioned embodiments, the main beam welding form may be not only heat conduction type welding but also keyhole type welding.

(Verification experiment 2)
Here, the result of the verification experiment 2 of the effect of the present invention will be described. The device configuration used in this verification experiment 2 is the configuration of the welding device according to the seventh embodiment and is the same as the welding device 100. The first experimental condition as a comparative example uses a configuration in which the diffractive optical element 123 is removed from the welding apparatus 100, and the second experimental condition corresponding to the present invention is that the irradiation surface shape is shown in FIG. The processing target W is provided with the diffractive optical element 123 designed to be irradiated with the laser beam with the profile described above, but the wavelength of the laser beam used is in the blue region. As common experimental conditions, the sweep speed between the optical head 120 and the workpiece W is set to 5 m / min, and nitrogen gas is used as the shield gas. The processing target W is tough pitch copper having a thickness of 2 mm.

More specifically, under the first experimental condition, a multimode fiber laser device with an oscillation wavelength of 1070 nm is used as the laser oscillator 110, and this is used with an output of 3 kW. Then, by irradiating the object to be processed as a single spot without passing through the diffractive optical element 123, the spot diameter of the condensing point is 100 μm, and its average power density is 3.8 × 10 ⁷ W / cm ² . ..

Under the second experimental condition, a semiconductor laser device with an oscillation wavelength of 450 nm is used as the laser oscillator 110, and this is used with an output of 1 kW. The diffractive optical element 123 used is designed so that the laser beam having the irradiation surface shape as shown in FIG. As for the output distribution, 300 W of the output of 1 kW is distributed to the semi-circular sub-beams almost evenly. At this time, the average power density of the main beam is 2.2 × 10 ⁶ W / cm ² , and the average power density of the sub-beam is 8.0 × 10 ⁴ W / cm ² .

  When the verification experiment was performed under the above experimental conditions, the following results were obtained.

  Under the first experimental condition, the power density at the condensing point exceeded the melting threshold of pure copper to form a keyhole and welding was possible, but at the same time, spatter and welding defects frequently occurred.

  On the other hand, under the second experimental condition, the copper material has a high absorptivity at a wavelength of 450 nm, even though the output of the laser oscillator was 1 kW, so that welding can be performed to a desired depth and the sweep direction It was also possible to form a front molten pool with a 300 W semicircular sub-beam arranged in the front. As a result, it was confirmed by high-speed camera observation that spatter and welding defects were significantly reduced to about 20% or less due to the effect of the front molten pool formed by the sub beam.

  Also from this verification experiment, the profile in the moving direction of the power density of the laser light L on the processing target W has a sub-beam located in front of the main beam in the moving direction. A welding apparatus and a welding method using the same, in which the wavelength of the laser beam forming the beam has a reflectance lower than the reflectance in the infrared region of the object to be processed, have the effect of suppressing the occurrence of spatter. Was shown.

  Although the present invention has been described above based on the embodiment, the present invention is not limited to the embodiment. What is configured by appropriately combining the constituent elements of the above-described embodiments is also included in the scope of the present invention. Further, further effects and modified examples can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

100, 200, 300, 400, 500, 600 Welding device 110, 210, 310, 411, 412, 510, 611, 612 Oscillator 120, 220, 320, 420, 520, 620 Optical head 121, 221, 321, 421a, 421b, 521a, 521b, 621 Collimating lens 122, 222, 322, 422a, 422b, 522a, 522b, 622 Condensing lens 123, 223, 323 Diffractive optical element 224a, 224b, 226, 324a, 324b Mirror 225a, 225b, 325a. , 325b Motors 130, 230, 330, 431, 432, 531, 533, 534, 631, 632, 635 Optical fiber 532 Branch unit 634 Coupling section

Claims (35)

Place the processing target in the area irradiated with the laser light from the laser device,
Irradiated portion while irradiating the laser light from the laser device toward the processing target while relatively moving the laser light and the processing target, and sweeping the laser light on the processing target. The above-mentioned processing target is melted and welded,
Including steps,
The laser light is composed of a main beam and a sub-beam having at least a part thereof in front of the sweep direction, and the power density of the main beam is equal to or higher than the power density of the sub-beam.
A method of welding a workpiece with a laser.   The welding method according to claim 1, wherein the power density of the main beam is at least strong enough to generate a keyhole.   The welding method according to claim 1, wherein the laser beam further has a sub-beam having a power density lower than that of the main beam, behind the main beam in a sweeping direction.   The welding method according to claim 1, wherein the laser beam further includes a sub-beam having a power density lower than that of the main beam, in a lateral direction of a sweep direction of the main beam.   The welding method according to claim 1, wherein the laser beam further has sub-beams having a power density lower than that of the main beam dispersed around the main beam.   The welding method according to claim 1, wherein the sub-beam has a ring shape surrounding the main beam or an arc shape that is a part of the ring shape surrounding the main beam.   2. The main beam and the sub beam of the laser light are configured such that the molten pool formed by the main beam and at least a part of the molten pool formed by the sub beam overlap each other. Item 8. A welding method according to any one of items 7.   The welding according to claim 1, wherein the wavelength of the laser beam that forms at least the sub beam of the main beam and the sub beam is a wavelength having a reflectance lower than the reflectance of the infrared region of the processing target. Method.   The welding method according to claim 8, wherein the wavelength of the laser beam that forms the main beam is the same as the wavelength of the laser beam that forms the sub beam.   The welding method according to any one of claims 1 to 9, wherein the main beam and the sub-beam are laser beams emitted from the same oscillator.   The welding method according to any one of claims 1 to 9, wherein the main beam and the sub beam are laser beams emitted from different oscillators.   The welding method according to any one of claims 1 to 11, wherein the main beam and the sub beam are formed by a bee shaper arranged between the oscillator and the processing target.   The welding method according to claim 12, wherein the beam shaper is a diffractive optical element.   The object to be processed is at least two members to be welded, and the step of arranging the object to be processed in a region irradiated with laser light is performed by superposing, contacting, or adjoining the at least two members. The welding method according to any one of claims 1 to 13, which is a step of arranging.   The welding method according to claim 1, wherein a beam diameter of the sub beam is substantially equal to or larger than a beam diameter of the main beam. A laser oscillator,
An optical head that receives light oscillated from a laser oscillator to generate laser light, irradiates the generated laser light toward a processing target, melts the processing target in the irradiated portion, and performs welding.
Composed by
The optical head is configured such that the laser light and the processing target are relatively movable, while sweeping the laser light on the processing target, performing the melting and welding.
The laser light is composed of a main beam and a sub-beam having at least a part thereof in front of the sweep direction, and the power density of the main beam is equal to or higher than the power density of the sub-beam.
A laser welding device that welds a workpiece with a laser.   The laser welding apparatus according to claim 16, wherein the power density of the sub-beam has a strength capable of melting at least the processing target.   The laser welding apparatus according to claim 16, wherein the laser beam further has a sub-beam having a power density lower than that of the main beam, behind the main beam in a sweeping direction.   The laser welding apparatus according to claim 16, wherein the laser light further includes a sub-beam having a power density lower than that of the main beam in a lateral direction of the main beam in a sweep direction.   The laser welding device according to claim 16, wherein the laser beam further has sub-beams having a power density lower than that of the main beam dispersed around the main beam.   17. The laser welding apparatus according to claim 16, wherein the sub beam has a ring shape surrounding the main beam or an arc shape that is a part of the ring shape surrounding the main beam.   17. The main beam and the sub beam of the laser light are configured such that a molten pool formed by the main beam and at least a part of the molten pool formed by the sub beam overlap each other. Item 22. The laser welding device according to any one of Item 21.   17. The laser according to claim 16, wherein the wavelength of the laser beam that forms at least the sub beam of the main beam and the sub beam is a wavelength having a reflectance lower than the reflectance of the infrared region of the processing target. Welding equipment.   24. The laser welding apparatus according to claim 23, wherein the wavelength of the laser beam forming the main beam is the same as the wavelength of the laser beam forming the sub beam.   25. The laser welding apparatus according to claim 16, wherein the optical head generates the laser light including the main beam and the sub beam from light emitted from a single laser oscillator.   The optical head includes a beam shaper arranged between the laser oscillator and the processing target, and the diffractive optical element forms the main beam and the sub-beam from light emitted from the single laser oscillator, The laser welding device according to claim 25.   27. The laser welding apparatus according to claim 26, wherein the beam shaper is a diffractive optical element.   23. The laser beam oscillator is configured by two different laser oscillators, and the main beam and the sub beam are laser beams emitted from the two different oscillators, respectively. The laser welding device according to 1.   29. The laser welding apparatus according to claim 16, wherein the processing target is at least two members to be welded.   The laser welding device according to claim 16, wherein a beam diameter of the sub beam is substantially equal to or larger than a beam diameter of the main beam.   27. The laser welding apparatus according to claim 26, wherein the beam shaper is rotatably provided. There are a plurality of laser oscillators,
23. The laser welding device according to claim 16, wherein the optical head internally combines lights emitted from the plurality of oscillators to generate the laser light. There are a plurality of laser oscillators,
23. The laser welding apparatus according to claim 16, further comprising a multi-core fiber that combines lights emitted from the plurality of laser oscillators and guides the lights to the optical head.   The laser welding apparatus according to claim 16, wherein the optical head is configured to be capable of sweeping the laser light with respect to the fixed processing target.   The laser welding apparatus according to claim 16, wherein the irradiation position of the laser light from the optical head is fixed, and the processing target is held so as to be movable with respect to the fixed laser light.

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